In image and data processing, various devices are known to effect positioning of objects on a graphic user interface. These objects are visualized on a display unit, e.g., a monitor, a large display panel or an LCD display. In practice, standard input devices are employed, e.g., keyboards equipped with a special keypad for effecting positioning, computer mice or input devices with a track ball. Other input devices of this type include joysticks, i.e., a lever-type operating element, or digitizing tablets.
A wide variety of forms of positioning are found in practice. On the one hand, the graphic user interface itself, a part thereof or, e.g., a greatly enlarged portion thereof, can be shifted on the display unit. This often occurs if the total displayable area is larger than the display area of the display unit. Furthermore, when a computer system is used, for example, it is constantly necessary to reposition graphic control markers. These markers are often referred to as cursors, insertion markers or mouse pointers and indicate the location where a change is to be made, e.g., by initiating a data input.
In the aforementioned input devices, electrical control signals are generated to mechanically effect position changes, e.g., by actuating keys or by scanning a rolling motion in XY direction. The control signals are transmitted to a processing unit, which thereby effects a position change, e.g., of a cursor on the display unit. This functionality requires the respective input device to be registered and activated, via system means, at the processing unit.
Furthermore, the user must at least get used to the movements at, or with, such an input device being spatially decoupled from the position changes that the device causes on the display unit. For example, a PC mouse is moved on a surface, whereas an associated position change occurs on a monitor. As a rule, the input device to be operated and the display unit are not simultaneously in the user's field of view.
German Patent DE 198 80 483 discloses an input device for a computer. Furthermore, German Patent DE 198 611 29 relates to a corresponding method for performing adjustments by means of an input device for a computer that has a graphic user interface.
Therein, the user interface of an application program running on a computer is displayed on a monitor and, in addition, projected onto a display area, e.g., a projection screen, by means of a projector. Thereby, several persons can view its content. With the aid of transmitters in the form of laser pointers, focused light beams can be directed at the display area. The respectively occurring light spots simulate a mouse pointer, and controllable contents of the graphic user interface displayed on the projection area can be activated at this location.
For activation, an image pickup device including a CCD sensor with an optics system, whose detection area includes at least the entire projection screen, is placed behind the projection screen. A control circuit detects the precise XY position of an incident light spot by a line and column analysis of the CCD sensor. Thereby, an electronic signal is generated, which is transmitted to the computer and which is characteristic for the location where the beam strikes the projection screen in the detection area and/or for the distance and direction of movement of the incident light spot. This simulates asynchronous mouse pointer positioning events and makes it possible to activate objects in the detection area.
This kind of mouse pointer simulation, however, has the drawback that a light spot itself, with the detection of its position on the projection screen and with an assignment to the controllable objects of a graphic user interface projected thereon, takes on the characteristic of an independent cursor. This cursor is not synchronous with the cursor that is displayed on the monitor of the associated computer and that is administered, for example, by means of a computer mouse. As a result, actions initiated by different cursors can affect the application program executed on the computer. For safety reasons, such a device cannot be used in an industrial environment, e.g., in a control room of a production line.
A further drawback of the devices disclosed in German patents DE 198 80 483 and DE 198 61 129 is that they require an image pickup device with a detection area that covers the display area, e.g., a large screen, completely. For this purpose, the image pickup device may have to be arranged at a substantial distance in front of or behind the projection screen and the light spots to be detected thereon. Since the XY coordinate position of a light spot and its movement is absolutely detected with respect to the dimensions of the detection area, the image pickup device must furthermore be calibrated relative to the projection screen. After this calibration, the image pickup device may no longer be shifted.
A further drawback is that the surface of the projection screen must reflect the incident light spot, since, otherwise, navigating and positioning by a user would not be possible. However, for screens, a reflection on the surface is not desirable. The device disclosed in German Patents DE 198 80 483 and DE 198 61 129 is therefore suitable, for example, as the display area in the case of a projection screen, but not in the case of a thin film transistor (TFT) display. Furthermore, the transmitter must generate a sharp, readily visible light spot to enable positioning by an operator. Therein, in particular in the case of large screens, laser radiation will have to be used in the transmitter. This, however, requires compliance with safety regulations.
German Patents DE 43 36 677 and DE 197 57 674 disclose input devices for positioning an object on a graphic surface. Therein, the position of a light spot in space is detected and the movement of this light spot is converted into a corresponding movement of the object.
The arrangement described in German Patent DE 43 36 677 is employed for determining a spatial position and for inputting control information into a system having a graphic user interface. Therein, the arrangement is equipped with at least one input device having a light source that is operated by a user, a camera arranged adjacent to the user interface of the system, and an acceleration sensor in the input device for detecting accelerations axially to the user interface. The arrangement makes it possible to determine the local position of the input device in order to control a cursor on the user interface. Employment of the acceleration sensor makes it possible not only to detect a movement perpendicular to the surface but also to signal user actions to the camera, e.g., the selection of objects or state changes in the program.
German Patent DE 197 57 674 discloses an arrangement for position detection and remote control. The object of this arrangement is to remote-control the position of a cursor, which is displayed on the display screen of a receiver, by two-dimensional or three-dimensional positioning of a transmitter. A further object of the known arrangement is to select a function by actuating an ON/OFF switch on the transmitter. The light emitted from a light source block of a transmitter is emitted via a first optical block. A receiver receives the light from the transmitter via a second optical block in a sensor block. A detection block detects the light intensity as a function of the output signal of the sensor block. A control block calculates the two-dimensional or three-dimensional position of the transmitter and displays this position as a cursor position on the display screen.
The input devices disclosed in the German Patents DE 43 36 677 and DE 197 57 674 have the drawback that a light source that generates the light spot must be moved substantially before the movement of the light spot can be detected. For a handheld light source, this usually requires the entire arm to be moved. A movement of the light source “from the wrist” is not possible.